Plastic composition, production method, and use of same

ABSTRACT

A plastic composition containing
         at least one weakly polar or apolar thermoplastic polymer;   at least one metallic salt of an unsaturated aliphatic fatty acid;   at least one first mediator which is a hydrocarbon compound having at least one cyclic group and having at least one polar substituent comprising an oxygen atom and/or nitrogen atom, wherein the first mediator comprises at least two cyclic groups per polar substituent, and wherein the melting point of the first mediator is no more than 80° C. below and no more than 50° C. above the melting point of the thermoplastic polymer; and   at least one third mediator which is a hydrocarbon compound having at least one cyclic and preferably aromatic group which is unsubstituted or halogen-substituted, wherein the boiling point of the third mediator is no more than 100° C. below and no more than 80° C. above the melting point of the thermoplastic polymer.

The invention relates to a highly filled plastic composition, to amethod of manufacturing the highly filled plastic composition, and tothe use of such a highly filled plastic composition.

The use of a filled plastic composition for manufacturing functionalcomponents is known from the prior art. Such compositions typicallycomprise a plastic matrix and a filler material.

A high filler material portion is desirable to improve some propertiesof such functional components. An increasing filler material portioncan, for example, produce an increase or a greater value of the thermalconductivity, of the density, of the magnetic properties, or of thescreening effect with respect to electromagnetic signals and ionizingradiation. A great improvement of some properties can in particular beobserved when the filler material portion is close to the theoreticalmaximum since the number of particle contacts increases greatly in thisrange. It is possible to speak of a proximity to the theoretical maximumwhen the volume fraction of the filler material comes close to thevolume fraction of the native filler material particles with a maximumpacking density. The volume fraction of the native filler materialparticles at a maximum packing density results directly from theparticle size distribution.

On the other hand, as the filler material portion increases, the meltviscosity of the plastic compositions also rises, whereby high-filledcompositions of this type are not accessible to every processingtechnology. Whereas molding compounds and casting compounds can behighly loaded with filler material in part at the cost of designfreedom, highly filled plastic compositions are often not suitable for aprocessing within the framework of a variable injection molding processor extrusion process. Furthermore, some mechanical properties of thecomponents are degraded by a high filler material portion and the highlyfilled components tend to be brittle.

It is the object of the invention to provide plastic compositions thatare as highly filled as possible that can be processed within theframework of an injection molding process or extrusion process and thatadditionally have acceptable mechanical properties.

Against this background, the invention relates to a highly filledplastic composition comprising (a) at least one polyolefin; (b) at leastone metallic salt of an unsaturated aliphatic fatty acid; (c1) at leastone first mediator which is a hydrocarbon compound having at least onecyclic and preferably aromatic group and having at least one polarsubstituent comprising an oxygen atom and/or nitrogen atom, wherein thefirst mediator comprises at least two and at most ten cyclic groups perpolar substituent, and wherein the melting point of the first mediatoris no more than 80° C. below and no more than 50° C. above the meltingpoint of the polyolefin (a); (c2) optionally at least one secondmediator which is different from the first mediator (c1) and is ahydrocarbon compound having at least one cyclic and preferably aromaticgroup and having at least one polar substituent comprising an oxygenatom and/or nitrogen atom, wherein the second mediator comprises fewerthan two cyclic groups per polar substituent and preferably at least twoand at most ten polar substituents per cyclic group, and wherein themelting point of the second mediator is no more than 80° C. below and nomore than 50° C. above the melting point of the polyolefin (a); (d) andat least one third mediator which is a hydrocarbon compound having atleast one cyclic and preferably aromatic group which is unsubstituted orhalogen-substituted, wherein the boiling point of the third mediator isno more than 100° C. below and no more than 80° C. above the meltingpoint of the polyolefin (a); and (e) at least one particulate fillermaterial.

The boiling point at normal pressure is to be understood as the boilingpoint.

The filled composition can be present in pellet form to be able to beprocessed, for example, within the framework of an extrusion process orinjection molding process. The composition can furthermore be present asa solid component that can be obtained, for example, using an extrusionprocess or an injection molding process.

The filler material portion of the highly filled plastic compositionamounts to more than 40 vol %, measured at the total volume of thefilled composition. In a preferred embodiment, the filler materialportion amounts to more than 50 vol %. In a further preferredembodiment, the filler material portion can amount to more than 60 vol%.

In an embodiment, the particular filler material (e) has a monomodaldistribution of the particle sizes. In an alternative embodiment, thefiller material has a multimodal distribution of the particle sizes.

The invention includes the idea that the filler material portion in thehighly filled plastic composition is close to the theoretical maximumthat results from the particle size distribution. With filler materialshaving a monomodal distribution of the particle sizes, the theoreticalmaximum is typically lower (for example at 65 vol % there) than withfiller materials having a multimodal distribution of the particle sizes(at 75 vol % there, for example). It has been recognized that a numberof physical properties of highly filled plastic compositions, forexample their thermal conductivity, depend less on the absolute fillermaterial portion than on the proximity of the filler material portion tothe theoretical maximum. The effect is presumably based on the fact thatthese effects are decisively influenced by the number of particlecontacts of the filler material and that this number increases greatlyclose to the theoretical maximum.

Provision is therefore made that the filler material portion in theplastic composition amounts to at least 80 vol %, preferably at least 90vol %, and further preferably at least 95 vol %, of the theoreticalmaximum.

The unfilled plastic composition can be combined under the term “organicmaterial”. In highly filled plastic compositions in accordance with theinvention or in plastic compositions in accordance with the inventionfilled close to the packing limit, it is assumed that the first mediator(c1) and optionally furthermore the second mediator (c2) contributes toan increase in the melt volume and to a degradation of the meltviscosity during the processing, that the first mediator (c1) andoptionally furthermore the second mediator (c2) in the completedcomponent contributes to an increase in the affinity or bond strengthbetween the organic material and the filler material, that the thirdmediator (d) forms a gas phase during the processing and thus furtherincreases the volume of the organic material and further degrades theviscosity, and that the salt (b) contributes to a homogenization of themixture.

In an embodiment, the filler material (e) is a metal powder, metal oxidepowder, an oxide ceramic powder, a non-oxide ceramic powder, or a carbonpowder. The use of mixtures comprising such powders is also conceivableand covered by the invention.

The filler material particles preferably have a spherical or granulardesign. In an embodiment, the average grain diameter of the fillermaterials is between 1 μm and 150 μm, preferably between 20 μm and 100μm. The average grain diameter of the filler materials can be determinedby sieve analysis in accordance with DIN 66165, for example.

In an embodiment, the melting point of the first mediator (c1) is nomore than 50° C. below and/or no more than 30° C. above the meltingpoint of the polyolefin (a).

In an embodiment, the melting point of the second mediator (c2) is nomore than 50° C. below and/or no more than 30° C. above the meltingpoint of the polyolefin (a).

In an embodiment, the melting point of the third mediator (d) is no morethan 70° C. below and/or no more than 50° C. above the melting point ofthe polyolefin (a).

The specified general, and preferred maximum, boiling point and meltingpoint differences between the ingredients (a), (c1), (c2), and (d) havethe background that, on the one hand, the polyolefin (a), the firstmediator (c1), and, where present, also the second mediator (c2) shouldbe present in a melted state during the processing and the thirdmediator (d) should be present in gaseous form during the processing,and that, on the other hand, none of the substances should decompose.The fact that the boiling point of the third mediator (d) can be up to100° C. below the melting point of the polyolefin (a) at normal pressureis due to the fact that local pressures of multiple bar can possibly beadopted during the processing that result in an increase of the boilingpoint.

In an embodiment, the polyolefin (a) has an average molar mass ofbetween 10⁴ and 10⁶ g/mol. The average molar mass of suitablepolyolefins (a) can, for example, be between 50,000 and 500,000 g/mol.

In an embodiment, the melting point of the polyolefin (a) is between100° C. and 250° C.

In an embodiment, the polyolefin (a) is a semicrystalline polymer havinga degree of crystallinity of less than 90%. The degree of crystallinitycan, for example, be between 30 and 80%.

In an embodiment, the polydispersity of the polyolefin (a) is less than5.

Suitable polyolefins (a) comprise polyethylene, polypropylene,polymethylpentene, polyisoprene, polybutylene, polyisobutylene, as wellas copolymers and mixtures thereof. Polyethylene is particularlypreferred.

The polyolefins (a) can be modified, for example oxidized, grafted orsilanized. Unsubstituted polyolefins without heteroatoms are preferred,however.

In an embodiment, the fatty acid of the salt (b) is a monovalentcarboxylic acid having more than 8 carbon atoms and at least one doublebond. The carboxylic acids preferably comprise fewer than 25 carbonatoms. The preferred number of double bonds is preferably between 1 and5. The number of carbon atoms can amount to between 15 and 20, forexample. The number of double bonds can amount to 1 or 2, for example.Suitable carboxylic acids include oleic acid and linoleic acid. Thecation of the salt can, for example, be an alkali metal, in particularsodium or potassium.

In an embodiment, the proportion of the salt (b) in the unfilledcomposition, i.e. in the organic material, amounts to between 1 and 15%by weight. Preferred ranges include proportions of more than 3% byweight and of less than 7% by weight.

In an embodiment, the first mediator (c1) comprises hydroxy groupsand/or amino groups as polar substituents. In an embodiment, all thepolar substituents of the first mediator (c1) are hydroxy groups and/oramino groups, preferably hydroxy groups.

In an embodiment, the first mediator has 1 to 4 (c1) polar substituentsand preferably hydroxy groups.

In an embodiment, the first mediator (c1) is a polycyclic aromaticalcohol.

Examples of suitable first mediators (c1) include triphenylmethanol,diphenylmethanol, 4-nitrobenzenemethanol, diphenylether,1,2,4-triphenylsilanol, hydroxybiphenyl, 3-hydroxybiphenyl,2-hydroxybiphenyl, □-cyclohexyl-α-phenyl-1-piperidinepropanol,4-cyclohexylphenol, 2-cyclohexylphenol, and dibenzylamine.

In an embodiment, the second mediator (c2) comprises hydroxy groupsand/or amino groups as polar substituents. In an embodiment, all thepolar substituents of the second mediator (c2) are hydroxy groups and/oramino groups, preferably hydroxy groups.

In an embodiment, the second mediator (c2) has 1 to 4 polar substituentsand preferably two polar substituents. In an embodiment, the secondmediator (c2) comprises an aromatic 6-ring having two polar substituentsand preferably hydroxy groups in a para position.

In an embodiment, the second mediator (c2) is an aromatic alcohol.

Examples of suitable second mediators (c2) include4-(3-hydroxy-1-propenyl)-2-methoxyphenol, 4-hydroxybenzenemethanol,4-hydroxybenzeneethanol, 3-hydroxybenzene-methanol,2-hydroxybenzenemethanol, 4-hydroxybenzene-ethanol, 4-benzylphenol,2-benzylphenol, 2-(benzyloxy)ethanol, 4-(2-aminopropyl)phenol,α-(1-aminopropyl) benzenemethanol, α-aminopropyl)-benzyl alcohol,o-ethylphenol, m-ethylphenol, p-ethylphenol, 2,4-xylenol, 2,5-xylenol,2,6-xylenol, 3,4-xylenol, 3,5-xylenol, benzeneethanol, α-methylbenzylalcohol, 3-methylbenzenemethanol, 4-methylbenzenemethanol,p-methylaniline, 4-tert-butyl-1,2-benzenediol,p-1-acetyl-2,5-dihydroxybenzene, α-allylbenzenemethanol,4-aminobenzeneethanol, 2-aminobenzenemethanamine,2-aminobenzenemethanol, α-(1-aminoethyl)benzenemethanol,4-(2-amino-1-hydroxyethyl)-1,2-benzenediol,α-(aminomethyl)benzenemethanol, 2-amino-4-methylphenol,4-amino-2-methylphenol, 4-amino-3-methylphenol,3-(aminomethyl)-3,5,5-trimethylcyclo-hexanol,α-(aminomethyl)benzenemethanol, α-(1-aminopropyl)benzenemethanol,1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol,benzeneethanol, benzenepentanol, benzenepropanol, 1,2,3-benzenetriol,1,2,4-benzenetriol, 1,3,5-benzenetriol, p-benzidine,1,1-bis(4-chlorophenyl)ethanol,2,5-bis(1,1-dimethylpropyl)-1,4-benzenediol, 1-butoxy-4-methylbenzene,2-tert-butyl-4,6-dimethylphenol, 4-tert-butyl-2,5-dimethylphenol,4-tert-butyl-2,6-dimethylphenol,1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene,2-tert-butyl-4,6-dinitrophenol,1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene,2-tert-butyl-4,6-dinitrophenol, 4-tert-butyl-1,2-benzenediol,2-tert-butyl-1,4-benzenediol, 2-tert-butyl-4,6-dimethylphenol,4-tert-butyl-2,5-dimethylphenol, 4-tert-butyl-2,6-dimethyl-phenol,2-tert-butyl-4-methoxyphenol, 3-tert-butyl-4-methoxyphenol,N,N-diethyl-2-methylaniline, 2,6-diisopropylaniline,3,4-dimethoxybenzenemethanol, 2,5-dimethyl-1,3-benzenediol,2,6-dimethyl-1,4-benzenediol, 4-dimethylbenzenemethanol,1-(4-methylphenyl)ethanol, α, α-dimethylbenzenemethanol, α-cumylalcohol, α-dimethylbenzenepropanol, 2-(1,1-dimethylpropyl)phenol,4-(1,1-dimethylpropyl)phenol, 2-(hydroxymethyl)-1,4-benzenediol,2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol,4-methoxy-α-methylbenzenemethanol, 2-methylaniline, 3-methylaniline,4-methylaniline, N-methylaniline, 3-methyl-1,2-benzenediol,4-methyl-1,2-benzenediol, 2-methyl-1,3-benzenediol,4-methyl-1,3-benzenediol, 5-methyl-1,3-benzenediol,2-methyl-1,4-benzenediol, α-methylbenzenemethanol,2-methylbenzenemethanol, 2-methyl-1,3-benzenediol,4-methyl-1,3-benzenediol, 5-methyl-1,3-benzenediol,2-methyl-1,4-benzenediol, 2-methylbenzeneethanol,4-methylbenzeneethanol, 2-methylbenzenemethanamine,3-methylbenzenemethan-amine, 4-methylbenzenemethanamine,N-methylbenzenemethanamine, α-methylbenzenemethanol,2-methylbenzenemethanol, 3-methylbenzenemethanol,4-methylbenzenemethanol, 3-methylbenzenemethanol,4-methylbenzenemethanol, α-methylbenzenepropanol,α-ethylcyclohexanemethanol, 4-methylcyclohexanemethanol,1-methylcyclohexanol, cis-2-methylcyclohexanol,trans-2-methylcyclohexanol, cis-3-methylcyclohexanol,trans-3-methylcyclohexanol, cis-4-methylcyclohexanol,trans-4-methylcyclohexanol, cis-2-methylcyclohexanol,trans-2-methylcyclohexanol, cis-3-methylcyclohexanol,trans-3-methylcyclohexanol, cis-4-methylcyclohexanol,trans-4-methylcyclohexanol, 1-methyl-4-isopropylcyclohexanol,5-methyl-2-isopropylcyclohexanol, 5-methyl-2-isopropylcyclohexanol,5-methyl-2-isopropylcyclohexanol, 5-methyl-2-isopropylcyclohexanol,5-methyl-2-isopropylcyclohexanol, 2-(methylphenylamino)ethanol,2-[(2-methylphenyl)amino]ethanol, 4-methyl-α-phenylbenzenemethanol,α-methyl-α-phenylbenzenemethanol, 2-(methylphenylamino)ethanol,2-[(2-methylphenyl)amino]ethanol, 4-methyl-α-phenylbenzenemethanol,α-methyl-α-phenylbenzenemethanol, 3-pentadecylphenol,trans-5-(2-phenylvinyl)-1,3-benzenediol,2,3,5,6-tetramethyl-1,4-benzenediol, 2,3,5-trim ethyl-1,4-benzenediol,2,3,3-trimethyl-2-butanol, cis-3,3,5-trimethylcyclo-hexanol,trans-3,3,5-trimethylcyclohexanol, 2,3,4-trimethylphenol,2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,4,5-trimethylphenol,2,4,6-trimethylphenol, and 3,4,5-trimethylphenol.

In an embodiment, the proportion of the first mediator (c1) in theunfilled composition, i.e. in the organic material, amounts to between 5and 30% by weight. Preferred ranges include proportions of more than 8%by weight and of less than 20% by weight.

In an embodiment, the proportion of the second mediator (c2) in theunfilled composition, i.e. in the organic material, amounts to between 1and 20% by weight. Preferred ranges include proportions of more than 2%by weight and of less than 10% by weight.

In an embodiment, the third mediator (d) is a hydrocarbon compoundhaving at least one cyclic and preferably aromatic group that has atleast one chlorine substitution.

The proportion of the third mediator (d) in the unfilled composition,i.e. in the organic material, can amount to between 3 and 20% by weight.Preferred volume fractions of the third mediator (d) compriseproportions of more than 5% by weight and less than 15% by weight.

In an embodiment, the third mediator (d) is an aromatic unsubstitutedhydrocarbon.

Examples of suitable third mediators (d) include benzene,dimethylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene,1,2,3-trimethylbenzene, p-ethyltoluene, m-ethyltoluene, o-ethyltoluene,isopropylbenzene, propylbenzene, p-xylene, m-xylene, o-xylene,ethylbenzene, 1,3,5-tri-tert-butylbenzene, (trichloromethyl)benzene,p-dichlorobenzene, hexamethylbenzene, hexylbenzene,1,2,4,5-tetramethylbenzene, 1,2,3,4-tetramethylbenzene,1,2,3,5-tetramethylbenzene, o-ethyltoluene, p-ethyltoluene,1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene,propylbenzene, isopropylbenzene, o-ethyltoluene, p-ethyltoluene,ethylbenzene, o-xylene, m-xylene, p-xylene, cyclohexane,methylcyclopentane, trimethylbenzene, i-sopropenylbenzene,m-diethylbenzene, p-diethylbenzene, sec-butylbenzene, tert-butylbenzene,isobutylbenzene, isopropylbenzene, o-ethyltoluene, m-ethyltoluene,p-ethyltoluene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene,1,3,5-trimethylbenzene, allylbenzene, (trans)-1,3-butadienylbenzene,1-tert-butyl-3,5-dimethylbenzene, butylbenzene, sec-butylbenzene,tert-butylbenzene, 1-tert-butyl-2-methylbenzene,1-tert-butyl-3-methylbenzene, 1-tert-butyl-4-methylbenzene,1-tert-butyl-4-ethylbenzene, 1-tert-butyl-2-methyl-benzene,1-tert-butyl-3-methylbenzene, 1-tert-butyl-4-methylbenzene,cyclopentylbenzene, cyclopropylbenzene, decylbenzene,1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene,1,2-diisopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene,1-ethyl-2,4-dimethylbenzene, 1-ethyl-3,5-dimethylbenzene,2-ethyl-1,3-dimethylbenzene, 1-isopropyl-2-methylbenzene,1-isopropyl-3-methylbenzene, 1-isopropyl-4-methylbenzene,1-methyl-3-propylbenzene, 1-methyl-4-propylbenzene,cis-1-propenylbenzene, cis-1-propenylbenzene, trans-1-propenylbenzene,1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene,1,2,4,5-tetramethylbenzene, 1,2,3,4-tetrahydronaphtalin andbicyclo[4.4.0]decane.

The weight proportion of the polyolefin (a) in the organic materialresults from the difference between the sum of the portions of thefurther additives and 100% by weight.

Further suitable esters include fatty acid esters. Fatty acid esterscan, for example, have an influence on the melt viscosity drop of theplastic composition and/or can serve the pretreatment of the fillermaterial (e). Further suitable additive include alkyl silanes. Furthersuitable additives include organic titanates, organic phosphonates, andorganic phosphates. Each of these additives can, for example, be presentin the composition in an amount between 0.1 and 5 vol. %.

Against the initially named background, the invention further relates toa method of manufacturing a filled plastic composition in accordancewith the invention comprising the steps: A suspending the fillermaterial (e) in a solvent; B mixing the salt (b), the first mediator(c1) and optionally the second mediator (c2) into the suspension; Cdrying the suspension for removing the solvent; D mixing the residuewith the polyolefin (a); and E adding the third mediator (d).

In the composition prepared in this manner, the salt (b) and the firstmediator (c1) and optionally the second mediator (c2) are not onlysimply present in the mixture, but rather adhere to the filler materialdue to the preceding surface treatment thereof.

A reaction phase can follow the admixing in accordance with step B priorto the drying in accordance with step C. The duration of this phase canamount to between 10 minutes and 2 hours, for example. Room temperatureor also an elevated temperature can be selected as the temperature. Anagitation of the suspension, by stirring for example, can take placeduring the reaction phase. Provision can alternatively be made that thesuspension is stationary during the reaction phase.

The mixing in accordance with step D can take place in the dry state,with the powdery, optionally previously ground residue from step C beingmixed with powder or granulated polyolefin (a). A mixing in the moltenstate of the polyolefin (a) is furthermore conceivable.

In an embodiment, the mixing in accordance with step D is followed by acompounding in the molten state, a cooling and a comminution.

The addition of the third mediator (d) in accordance with step E cantake place by spraying the comminuted dry mixture with the thirdmediator (d).

Suitable solvents comprise weakly polar to apolar solvents. Examplesinclude:

Suitable solvents include polar solvents, for example aprotic polarsolvents such as acetone or protic polar solvents such as ethanol.

The invention finally relates, against the initially named background,to the use of a highly filled plastic composition in accordance with theinvention for manufacturing a molding as part of an extrusion process orinjection molding process.

The present invention provides the possibility of achieving a degree ofvolume filling of the filler material in the polyolefin in a sensiblemanner from a technical processing and mechanical aspect that is veryclose to the theoretically maximum packing density of the native fillermaterial powder particles. Specific physical properties of the fillermaterial such as magnetic properties or thermal conductivity can thushave a very strong effect in the plastic composition so that new arease.g. in metal replacement can be opened up.

Further details and advantages of the invention will be explained in thefollowing with reference to the prior art, to the demands made and tothe presumed kind of cooperation of the filler material particles andthe matrix. It must be noted here that these embodiments have anexplanatory meaning and not a restrictive one, for example with regardto the required presence of a specific substance.

The compositions in accordance with the invention can be considered inan embodiment as a thermoplastic, organically modified plasticcomposition for the manufacture of highly packed plasticizableplastic-bonded powders/fibers/carbon nanotubes, whiskers or highlyfilled thermoplastics as a material for injection molding, extrusion,and similar processes. Applications include plastics having improvedphysical properties such as thermal conductivity, magnetic phenomena,high density, attenuation of ionizing radiation, screening from radiofrequency and the effect of abrasion, and feedstocks for MIM and CIMprocesses as well as 3D printing processes.

Such materials have to satisfy different demand profiles in dependenceon the application. Examples include those named in the following. Amodified polymer system for this application has to satisfy thefollowing demands in the completed component. It provides the materialwith its mechanical properties such as tensile strength, modulus ofelasticity, durability, temperature resistance, hardness, and abrasionresistance. These demands apply both to the polymer per se and to thebinding to the powdery/fibrous filler material. It must be chemicallyresistant with respect to environmental conditions and the process andapplication conditions. It must plasticize the total materialsufficiently, also at very high packing or at high degrees of fillingand must enable a complex shape typical for plastic injection moldingboth during the compounding of the material and during the componentmanufacture. Equally, a layer must be produced on the adhesion/bondassociated filler material surface that has excellent lubricationproperties and withstands very high pressures. It must have a very lowmelt viscosity that is substantially lower than that of the nativepolymer. It must be able to compensate the difference in the packingdensity between the filler material in flow movement and the fillermaterial resting in the very dense packing by a temporary volumeincrease. The solidification and crystallization behavior may notgenerate internal stresses that are too high in the component. Despitethe strong bonding to the filler material particles in the heat underplasticization conditions, an easy demolding capability out of the toolmust be ensured under solidification conditions.

In the prior art, the theoretically maximum achievable packing densityof the powder is currently not even only approximately reached in theabove-named applications with any material. The polymer preparations onthe basis of polyolefins at best enable contents with globular monomodalpowders that are ≥10 vol. % below the values of approximately 65 vol. %packing density with monomodal powders d90<45 μm which can be calculatedin accordance with the formula of LEE for particle size distributions.The values are even further removed with irregular morphologies, e.g.spaltered or plate-like morphologies. There is generally both asignificant deterioration of the flow properties in the processing ininjection molding and in particular of the mechanical properties from asearly as >55 vol. % powder portion with the above-named powders sincethe bonding of the polymer to the powder surface is not sufficientlystrong. The limit for tungsten screening materials at a density of 11g/cm³ is therefore currently at the screening power of lead (14 g/cm3with a screening power >50% above lead should be possible) or the heatconductivity of an isotropic thermal conductivity plastic at 2-3 W/mK(10-15 W/mK should be possible according to Lewis & Nielsen on reachingthe theoretical packing density). The same disproportion is also presentin permanently magnetic and soft magnetic materials whose mechanicalstrengths additionally drop by a large amount. In the examples named asexemplary of the density previously achieved and achievable inaccordance with the invention, the degree of volume filling increaseamounts to approximately 9 vol. %, but the absolute volume of the fillermaterial increases by close to 50% in the unchanging plastic volume,however. Synthetic resins for molding materials and casting materialsand, recently chain-shortened polyolefins, achieve slightly bettervalues.

Polyolefins are used in accordance with the present invention. There isgreat commercial interest in highly filled compositions based onpolyolefins. With the selected filler materials, above all polarmaterials such as metal and metal oxide powder as well as oxide ceramicpowder and optionally non-oxide ceramic powder are considered, butparticularly for the apolar polyolefins, apolar filler materials such asgraphite, graphene, or carbon nanofiber are also of interest. A modularsystem of selected organic additives has been developed for highlyfilled thermoplastics to modify the base polymer. This enables theproduction of highly packed plasticizable plastic-bonded powders or ofhighly filled thermoplastics as materials for injection molding,extrusion and similar processes. The modular system enables the directinfluencing of singular and multiple properties of the modified plasticboth during the component manufacture and in the completed component.This invention is thus delineated from the developments of recent worksthat have attempted to lower the viscosity of the filled plastics by theuse of multimodal powder mixtures. Since the flow improvements here onlyallow an increase of the packing density, the physical propertiesdegrade since the degree of volume filling cannot be increased to thesame degree since the polymer melt lacks wetting capacity andlubrication film volume.

The properties of adhesion/bonding, viscosity, volume, strength, impactresistance, sliding or demolding can be set in a modular manner, withthem not only being combined in a singular manner, but also in amultiple manner and at times synergistically. The melt viscosity ofpolar polymers is no longer sufficient for the implementation of highpacking levels with a sufficiently complete and simultaneously movablewetting. Said melt viscosity has to be greatly reduced without apermanent loss of the molecular structure and without a drop of theforce of adhesion/bonding at hydrophilic surfaces. In the sense of thisinvention, this is initially done by partial substitution of the highlyviscous polymer melt viscosity having low-viscous solvent viscosity andsalt melt viscosity of suitable protic solvents and organic salts thatare thermodynamically compatible with the polymer melts with respect totheir boiling points and melting points. The viscosity obtained issubstantially lower. The wetting capacity of a given melt volume thusincreases a lot. To further increase the wetting capacity and toincrease the lubrication film volume, the melt volume is furthermoresimultaneously temporarily greatly increased, with primarily the meltvolume of the liquid phase being increased whose volume growth is arequirement for the additional introduction of a secondary defined gasvolume that additionally inflates the primarily generated liquid volumeby the gas volume portion.

The exact function of the dissolving of the polymers is not looked at inmore detail here since it is basically known and is only used in aninnovative manner here. The greater polarity of the additives in asuitable solution is in particular used, beyond the very highviscosity-reducing effect, to obtain a large increase in the adhesiveforce toward the polar filler material by the diffusion-controlledlowering of the cohesive force of the polymer. The polyolefin meltsrequires first mediators and from case to case also second mediators asdefined above whose melting points are in the vicinity of the meltingtemperature. The melt volume of the polymer can be greatly increased byhigh volume fractions of these alcohols in the polymer.

The first mediator additionally acts as a plasticizer for thepolyolefins and thanks to their amphiphilic properties improve theadhesion between polar filler materials and the apolar or weakly polarmatrix and thus the incorporation of filler material particles bypromoting the penetration of the polymer chains within the particlestructure of the filler material. The second mediator, if admixed, canfurthermore demonstrate amphiphilic effects since it is more polar thanthe first mediator and can improve the adhesion to polar filler materialparticles. The polar substituents should, however, preferably beoriented such that they do not enter into any intramolecularassociations. A smaller volume fraction of third mediator added in theliquid state, but that is gaseous under melting conditions, results in afurther volume increase. The solvents additionally have a newlyrecognized effect on the impact resistance. The plasticizing effect ofthe condensed solvent phase in the solidified polymer has a similareffect to an elastomer. The miscibility and homogenization of thepolyolefin melts with the alcohol melts is improved by the addition ofthe fatty acid salts. The salts additionally act as lubricant at hightemperatures and as demolding means at lower temperatures. Theyfurthermore have a strength-promoting effect on crystallization.

Further details and advantages of the invention result from thefollowing described embodiment.

EMBODIMENT

34.1 parts by volume of aluminum powder are added to 41.8 parts byvolume of acetone in a suitable vessel and are stirred well. An aluminumpowder having the following grain size classification is used as thealuminum powder: d5<10 μm, d10<15 μm, d20<20 μm, d50<25 μm, d70<30 μm,d80<35 μm, d100<145 μm. 1.1 parts by volume of sodium oleate, 3.3 partsby volume of triphenylmethanol, and 1.1 parts by volume of4-hydroxybenzenemethanol are added to this suspension, are stirred andleft at room temperature for 30 min.

The suspension is subsequently dried.

The dried mixture is subsequently mixed with 15.4 parts by volume of HDpolyethylene by stirring. HD polyethylene has a degree of crystallinityof <90% and a mean molar mass of <150,000 g/mol. 3.2 parts by volume ofdimethyl benzene are sprayed onto this powder mixture. The total mixtureis homogeneously mixed by stirring in a simple mixer.

The obtained powdery composition is compounded in a sigma kneader andgranulated in a mill ready for injection molding.

As a result, a thermoplastic injection-moldable composition of HDpolyethylene and aluminum powder having a filler material portion of 62vol. % is obtained. The theoretically maximum filler material portion onthe use of said powder would amount to 65% by volume.

A cylindrical disk as per DIN is injection molded and is subjected to athermal conductivity measurement according to the hot disk method (ISO22007-2 at normal pressure and at 21° C.) at the Linseis THB-100 to testthe molded components obtainable from this composition. The thermalconductivity measured (that is isotropic due to the isometric fillermaterial) amounted to 8 W/mK.

Selected mechanical properties (elongation at break, strength, hardness)were significantly better on a qualitative comparison for the embodimentwith other highly filled materials known on the market. The high fillingand the good thermal conductivity are therefore less to the disadvantageof these mechanical properties than with known materials.

1. A highly filled plastic composition comprising: (a) at least onepolyolefin; (b) at least one metallic salt of an unsaturated aliphaticfatty acid; (c1) at least one first mediator which is a hydrocarboncompound having at least one cyclic and preferably aromatic group andhaving at least one polar substituent comprising an oxygen atom and/ornitrogen atom, wherein the first mediator comprises at least two and atmost ten cyclic groups per polar substituent, and wherein the meltingpoint of the first mediator is no more than 80° C. below and no morethan 50° C. above the melting point of the polyolefin (a); (c2)optionally at least one second mediator which is different from thefirst mediator (c1) and is a hydrocarbon compound having at least onecyclic and preferably aromatic group and having at least one polarsubstituent comprising an oxygen atom and/or nitrogen atom, wherein thesecond mediator comprises fewer than two cyclic groups per polarsubstituent and preferably at least two and at most ten polarsubstituents per cyclic group, and wherein the melting point of thesecond mediator is no more than 80° C. below and no more than 50° C.above the melting point of the polyolefin (a); and (d) at least onethird mediator which is a hydrocarbon compound having at least onecyclic and preferably aromatic group which is unsubstituted orhalogen-substituted, wherein the boiling point of the third mediator isno more than 100° C. below and no more than 80° C. above the meltingpoint of the polyolefin (a); and (e) at least one particulate fillermaterial; wherein the proportion of the filler material (e) amounts tomore than 40 vol. % measured at the total volume of the filledcomposition and/or more than 80 vol. % of the theoretical maximum.
 2. Ahighly filled plastic composition in accordance with claim 1,characterized in that the melting point of the first mediator (c1)and/or the melting point of the second mediator (c2) is no more than 50°C. below and/or no more than 30° C. above the melting point of thepolyolefin (a); and/or in that the boiling point of the third mediator(d) is no more than 70° C. below and/or no more than 50° C. above themelting point of the polyolefin (a).
 3. A highly filled plasticcomposition in accordance with claim 1, characterized in that the fillermaterial (e) is a metal powder, a metal oxide powder, an oxide ceramicpowder, a non-oxide ceramic powder, a carbon powder, or a combinationthereof; or in that the filler material (e) comprises a metal powder, ametal oxide powder, an oxide ceramic powder, a non-oxide ceramic powder,a carbon powder, or a combination thereof.
 4. A highly filled plasticcomposition in accordance with claim 1, characterized in that theaverage grain diameter of the filler materials is between 1 μm and 150μm.
 5. A highly filled plastic composition in accordance with claim 1,characterized in that the polyolefin (a) has an average molar mass ofbetween 10⁴ and 10⁶ g/mol; and/or in that the melting point of thepolyolefin (a) is between 100° C. and 250° C.
 6. A highly filled plasticcomposition in accordance with claim 1, characterized in that the fattyacid of the salt (b) is a monovalent carboxylic acid having more than 8carbon atoms and having at least one double bond.
 7. A highly filledplastic composition in accordance with claim 1, characterized in thatthe portion of the salt (b) amounts to between 1 and 15% by weight, andpreferably between 3 and 7% by weight, measured at the total mass of thecomposition without filler material.
 8. A highly filled plasticcomposition in accordance with claim 1, characterized in that the firstmediator (c1) and/or the second mediator (c2) comprises/comprise hydroxygroups and/or amino groups, preferably hydroxy groups, as polarsubstituents.
 9. A highly filled plastic composition in accordance withclaim 1, characterized in that the proportion of the first mediator (c1)amounts to between 5 and 30% by weight and preferably between 8 and 20%by weight, measured at the total mass of the composition without fillermaterial; and/or in that the proportion of the second mediator (c2)amounts to between 1 and 20% by weight and preferably between 2 and 10%by weight, measured at the total mass of the composition without fillermaterial.
 10. A highly filled plastic composition in accordance withclaim 1, characterized in that the proportion of the third mediator (d)amounts to between 3 and 20% by weight and preferably between 5 and 15%by weight, measured at the total mass of the composition without fillermaterial.
 11. A method of producing a highly filled plastic compositionin accordance with claim 1, said method comprising the following steps:A. suspending the filler material (e) in a solvent; B. mixing the salt(b), the first mediator (c1) and optionally the second mediator (c2)into the suspension; C. drying the suspension for removing the solvent;and D. mixing the residue with the polymer (a); and E. adding the thirdmediator (d).
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